1. Field of the Invention
The present invention relates to the field of data processing. More particularly, this invention relates to an apparatus for storing data in an array of bitcells, wherein access to a selected bitcell in the array of bitcells requires assertion of a wordline pulse on a wordline associated with a row in which the selected bitcell is to be found.
2. Description of the Prior Art
In the context of an apparatus for storing data in an array of bitcells it is known that the duration of wordline pulse which a given bitcell requires in order to be able reliably to perform a read or write operation can vary in dependence on a range of factors. For example, the particular level of the supply voltage provided to the bitcell array and the temperature at which the bitcell array is operating can cause the wordline pulse duration threshold (defining the boundary between successful and unsuccessful operation) to vary. However, other factors such as fluctuations in component sizes due to manufacturing variation are also known to have an effect. These variations can be local—at the level of individual components—or globally across, say, an entire integrated circuit (e.g. variations in oxide thickness). As a result, it is known to adopt a “worst-case” design approach, where parameters such as the wordline pulse duration and the supply voltage are set to incorporate a safety margin such that reliable and robust operation of the apparatus containing the bitcell array can be ensured. There is however an undesirability to this approach in that the setting of the wordline pulse duration and supply voltage to cater for the worst-case scenario necessarily means that in many instances greater energy is being expended to operate the system than is strictly necessary.
In addition, as the development of bitcell designs pushes to smaller technology scales and lower supply voltages, the impact of these known variabilities increases and, according to the prior art techniques, would require an ever greater relative margin to be used in order to ensure reliable operation. However, in association with the drive towards smaller technology scales and lower supply voltages, there is also pressure to provide data storage devices which consume less energy and such increased margining does not align well with this goal.